Sent home with 3 min contractions?

So I wait till my contractions are 3 minutes apart as I've always been told, I got to the hospital and I was dilated 2 cm and 75% effaced, and -3 but she felt the head, they monitored me for 2 hours and the entire time I was contracting 3 minutes apart but I didn't dilate anymore so they sent me home, I'm still having contractions what in the world am I supposed to do with painful contraction every 3 minutes? How am I supposed to know when in in labor now? My water will not break on its own!